This invention relates to hub clutches and more particularly to such a clutch for the front wheels of a four wheel drive vehicle.
In FIG. 1, there is shown a conventional hub clutch for the front wheels of a four wheel drive vehicle. This clutch comprises a drive clutch 1 having coupling teeth 2 connected to a power shaft, a driven clutch 3 having coupling teeth 9 and a spline 4 axially provided at its outer periphery, a case 5 having a spline 6 axially provided on its inner surface which is coupled with a wheel hub 7 by a plurality of bolts 8, and coupling means 10 having a spring 11 to provide a preload on the driven clutch 3 toward the drive clutch 1. The spring 11 is positioned in a sleeve-like space which is formed of a sleeve member 11a and a lower portion of the driven clutch 3. The sleeve member 11a is provided with grooves 11b to hold a pair of washers 20 and 21 between which the spring 11 is inserted. Further, four snap rings 11C are installed in the sleeve-like space to control the axial movement of the washers 20 and 21. In operation, the torque of the drive clutch 1 is conveyed to the driven clutch 3 through the coupled teeth 2 and 9 as the movement of the driven clutch 3 is effected toward the drive clutch 1 by the coupling means 10. This causes the case 5 to rotate in the connection between the spline 4 of the driven clutch 3 and inner spline 6 of case 5. Thus, the wheel hub 7 is forcedly rotated by the bolts 8 coupling the case 5 therewith.
In this prior hub clutch, there have been observed several drawbacks as follows.
(1) The manufacture of the case 5 requires additional processes for the spline 6 provided at the inner surface of case 5,
(2) The case 5 is enlarged in diameter because a plurality of the bolts 8 are annularly positioned to be axially inserted through the case 5 at its outer periphery,
(3) The case 5 is manufactured of a material having a high mechanical strength because the case 5 is adapted to convey the torque of the driven clutch 3 to the wheel hub 7,
(4) The manufacture of the sleeve member 11a and the driven clutch 3 is very difficult because they have spline grooves, and
(5) The construction of the coupling means 10 is very complicated because many snap rings etc. are required.